io.netty.handler.ssl.PseudoRandomFunction Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright 2019 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.handler.ssl;
import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;
import io.netty.util.internal.EmptyArrays;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.GeneralSecurityException;
import java.util.Arrays;
/**
* This pseudorandom function (PRF) takes as input a secret, a seed, and
* an identifying label and produces an output of arbitrary length.
*
* This is used by the TLS RFC to construct/deconstruct an array of bytes into
* composite secrets.
*
* {@link rfc5246}
*/
final class PseudoRandomFunction {
/**
* Constructor never to be called.
*/
private PseudoRandomFunction() {
}
/**
* Use a single hash function to expand a secret and seed into an
* arbitrary quantity of output.
*
* P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
* HMAC_hash(secret, A(2) + seed) +
* HMAC_hash(secret, A(3) + seed) + ...
* where + indicates concatenation.
* A() is defined as:
* A(0) = seed
* A(i) = HMAC_hash(secret, A(i-1))
* @param secret The starting secret to use for expansion
* @param label An ascii string without a length byte or trailing null character.
* @param seed The seed of the hash
* @param length The number of bytes to return
* @param algo the hmac algorithm to use
* @return The expanded secrets
* @throws IllegalArgumentException if the algo could not be found.
*/
static byte[] hash(byte[] secret, byte[] label, byte[] seed, int length, String algo) {
checkPositiveOrZero(length, "length");
try {
Mac hmac = Mac.getInstance(algo);
hmac.init(new SecretKeySpec(secret, algo));
/*
* P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
* HMAC_hash(secret, A(2) + seed) + HMAC_hash(secret, A(3) + seed) + ...
* where + indicates concatenation. A() is defined as: A(0) = seed, A(i)
* = HMAC_hash(secret, A(i-1))
*/
int iterations = (int) Math.ceil(length / (double) hmac.getMacLength());
byte[] expansion = EmptyArrays.EMPTY_BYTES;
byte[] data = concat(label, seed);
byte[] A = data;
for (int i = 0; i < iterations; i++) {
A = hmac.doFinal(A);
expansion = concat(expansion, hmac.doFinal(concat(A, data)));
}
return Arrays.copyOf(expansion, length);
} catch (GeneralSecurityException e) {
throw new IllegalArgumentException("Could not find algo: " + algo, e);
}
}
private static byte[] concat(byte[] first, byte[] second) {
byte[] result = Arrays.copyOf(first, first.length + second.length);
System.arraycopy(second, 0, result, first.length, second.length);
return result;
}
}